The Friday session was interrupted several times as Presiding Judge Richard May repeatedly warned Mr Milosevic his questions were improper and his comments were out of order.
Mr Milosevic has denied responsibility for ethnic Serbs accused of killing non-Serbs in Croatia in the early 1990s, saying they were defending themselves against Croatian pogroms.
Mr Milosevic is in the dock on more than 60 charges of war crimes and crimes against humanity and faces life behind bars if convicted.
His comments, made as he cross-examined a prosecution witness at the trial, give a glimpse into his likely defence against charges that Serb rebels acted on his instructions when they committed war crimes in Croatia and Bosnia.
"There was no aggression from Serbia. It was a civil war [in Croatia]," Mr. Milosevic said. "The Serb people had war imposed on them, and furthermore it was a war of self-defence."
'Not relevant'
After another lengthy period of cross-questioning, Judge May intervened to warn him: "You are rehearsing at great length and, if I may say so, with much repetition, that crimes were committed against Serbs.
Milosevic charges
Bosnia
Croatia
Kosovo
"That may or may not be so, but it is not relevant to our determining whether crimes were committed by you or by others."
"What you're trying to do is argue your whole case through this one witness, and it's a waste of the court's time," Mr May said.
"It's your case [to defend] but if I may say, you should be concentrating on challenging what this witness has to say... not simply on crimes committed by the other side."
The British judge said that even if Mr Milosevic could prove Croatians had committed war crimes, it would not absolve him of the charges alleged in prosecutors' indictment.
Mr Milosevic, who has refused to enter a plea over the war crimes charges against him, hit back: "I wish to remind you that I am not concealing my view that what you call an indictment is a false indictment, primarily for two reasons.
"First of all, no aggression took place, it was a civil war, and secondly the Serbian people had this war imposed upon them both in Croatia and in Bosnia," he said.
"It is evident they were defending the territory where they lived and were trying to avoid pogroms such as those perpetrated 50 years earlier. That is the only truth I am trying to explain here."
And denying he was contending that the other side was equally guilty, he insisted: "I have committed no crimes."